1. Field of the Invention
The present invention is directed to an improved vacuum cleaner tool and, in particular, to a vacuum cleaner tool having a motor-driven, rotary agitator brush therein. The rotary brush may be mounted in the tool housing in either of two positions, with the brush extending from the housing by different amounts depending upon which of the two positions the brush is mounted, and the distance from the brush axis to the center of a pulley connected to the motor remains constant in either of the two positions of the brush. Further, a relatively small diameter bearing is used and a bearing structure is provided therefor.
2. Description of the Prior Art
It is conventional in vacuum cleaner tools to use rotary agitators such as a rotary brush which extends from the vacuum cleaner tool housing to contact and agitate a surface to be cleaned. Rotary brushes of this type are driven by either electric or vacuum-powered motors which are coupled to the rotary brush by means of a pulley on the motor shaft and a drive belt coupling the pulley to the rotary brush.
One of the problems in the prior art vacuum cleaner tools of this type is that, as a result of use, the bristles of the brush become worn and thus the distance which the brush extends from the housing is reduced. At some predetermined point, the bristles become too worn and the agitator brush is ineffective.
Prior art vacuum cleaners, such as that shown in U.S. Pat. No. 2,707,792, have means for varying the distance which the brush extends from the housing. In devices such as that shown in this patent, a cap on the end of the rotary brush has a hub which may be mounted in the housing in either of two positions to vary the distance which the rotary brush extends from the housing. However, in devices such as that shown in U.S. Pat. No. 2,707,792, when the brush is shifted from the first position to the second position by the rotation of the hub, the distance between the drive pulley and the rotary brush is changed, thereby changing the length of the drive belt. This results in a decrease in efficiency, since the drive belt is no longer tensioned for optimum performance.
Other prior art vacuum cleaner tools, such as those shown in U.S. Pat. Nos. 2,612,483; 3,005,224 and 3,639,941 have structure for varying the tension of a pulley belt which drives the rotary brush. However, in each of these patents, the structure for varying the tension is a camming device in which the axle of the rotary brush is positioned in an inclined slot so that it can move in the slot in order to maintain a constant belt tension. Conventional tools of this type do not have provisions for varying the distance which a brush extends from the housing by predetermined amounts.
Another problem often encountered in prior art vacuum cleaner tools is their efficiency in edge cleaning; that is, the efficiency of the tool in cleaning a portion of a surface which is located near the edge of the tool. In prior art tools, such as those shown in U.S. Pat. Nos. 2,607,069; 2,707,792; 2,734,211; 2,785,431; 3,225,374; 3,959,847 and 4,221,019, bristles on the periphery of the rotary brush are not positioned near the edges of the rotary brush or they are positioned close to the edge only because the brush has a relatively large diameter dowel, because the mounting structure which mounts the brush axle onto the housing requires that a large bore be drilled in the end of the brush, thus making it difficult to have a sufficient depth at the edges of the dowel of the rotary brush to implant the bristles.